Our invention pertains to a coking process of hydrocarbon feedstocks, heavy distillation products or residues. More particularly, it pertains to the subsequent coke recuperation stage (decoking) following laydown within the reactor.
Coking is a well-known process in the refining industry, the objective of which is to upgrade heavy fractions and, more especially, the distillation residues by subjecting them to heat decomposition.
This usually occurs in large empty reactors where decomposition takes place in the form of distillates, which are removed from the reactor, and a coke deposit which gradually accumulates within the reactor.
The feedstock is usually introduced via the bottom of the reactor and, this being the case, coke is initially deposited in the lower part of the reactor, whence it progressively rises until it the latter is completely filled.
At this point, load injection is stopped and diverted to a second empty reactor.
This initial, coke-depositing stage is followed by a second stage in which the coke produced is recuperated.
To this end, once the reactor has been cleared of any residual hydrocarbons and has been cooled, it is opened at the top and at the bottom and a hole is excavated by means of the appropriate tools. The latter are usually carried by a scaffolding structure or a derrick which enables excavation within the reactor from above. The scaffolding structure (of which there is one per reactor--there are at least two reactors) is set up above the reactors which, in turn, are placed well above ground level to enable load injection and, more especially, recuperation of the resultant coke, which drops via gravity within the reactor and is then evacuated and transported to a storage area or to the utilizer.